small grape-like clusters of elastic sacs located at the ends of the bronchiopulmonary segments and surrounded by capillaries

alveolar walls

one layer of simple squamous epithelium; where O2 and CO2 are exchanged

septal cells

type of aveolar cell that produces fluid that moistens the cell and releases surfactant to keep alveoli from collapsing following expiration

ventilation

air flows between the atmosphere and the alveoli of the lungs because of alternating pressure differences created by the contraction and relaxation of respiratory muscles.

rate of airflow and breathing effort

is influenced by alveolar surface tension, compliance of the lungs and airway resistance

breathing

requires muscular activity and changes in chest size (thoracic cavity); air moves into lungs when pressure inside lungs is less than atmospheric pressure; air moves out of the lungs when pressure inside lungs is greater than atmospheric pressure

aka inspiration; contraction of the diaphragm (goes down) and external intercostal muscles increases the size of the thorax (lift ribs up), decreasing pressure in the thorax - air rushes in - the lungs expand

each gas in a gas mixture exerts its own pressure (think of pressure as a concentration) as if no other gasses are present; total pressure of a gas mixture is the sum of the partial pressures of all the gasses = p

Henry’s Law

the amount of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility coefficient (attraction for water); explains why divers can get the bends if they surface to quickly.

controls the basic rhythm of respiration within two areas: inspiratory - sets the basic rhythm of respiration proprioceptors in joints and muscles activate inspiratory center during exercise to bring in more oxygen; expiratory - activated during high levels of ventilation controls the muscles used during forced expiration